Hygrometer



C. E. LEWIS June 16, 1936.

HYGROMETER Fil ed Jan. 12, 1934 In? X 2162/ $6 ii 7 fw/vgnior WJBZhisAiiorg /eys Patented June 16 1936 'ihisinvention-relates tohyemmetesan m r partiqiflarlv .tcra: barometer-ad pted. t ac u ately anddirectly indicate the relative hmnidity oi airuqr. joiner gaseous .1 mium wh c it is bjected; withouteomputation at dat o in o mation.

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hygroscopic Fi: 1 1sa frontelevatibn of embodiment of Fig. 3 is avertical section taken on;:the "line E114s ow n vfihea mk ne mechanismMinneapolis,

linrilzontallyflegttefldling spaced. slots 62 to readily prrmt aceess ora'irw the interior of thehousing or frame. 'Theiiertica1*side walls' ofthe Tfafiie are provided with elongated slots 13 wincn are also for thepurposeof "admitting air totheinterior oftheHd' g.

shbwnt working mechanism ofhygrorne'ter; with the exception of theindicating pemt'ei is asser'nhled theffoim of a uhit de ta'cliahlyseduiiedfwithin" the frame 6r housing. The hnitiir'i-cludes *"a mountingplate l4 disposed. vertically; "as shown, "and 'detachably" 'se'cui''dto the interior of the name '6 andpositicnd" "amill ithtlie from side ofsaid frame. The scale 8 may-be Secured tot-he iorward face of mountingplate I 4 properposition to regi'ste'r' with the viewing aperturesa;

The pointer actuating 'rriecha nism comprises "a bellcrank lever IE'preIerably clispO'sed ina plane extending-parallel to themountingplatef4 and pivotally mounted on a suitable bracket l6 which is secured tothe mounting plate. Bracket l6, as shown, comprises a pair of spacedL-shaped plates spaced apart hy "spacing sleeves' I 6a and seciiredtowmounti'ng plate l4 adjacent the'uppererid 2 5 the'fehf. "lBell crankileve'r l5 has an upwardly exter'i'dlngarm. I 5a terminating' in a'"g"ears'egmnt 'l5b, J the geared -edge "of which extendsconcentricallyof the pivot for lever 15. Gear segment l5b is in constantmesh with a relatively small pinion I! "fixed 'to the indicator shaftl8. Indicator shaft i8 is journaled'in suitable=bearingsiprovidedby'bracket l6 and the mou'nting platenl l and extends normally withrespect to mounting plate H, the forward endthereof projecting-throughthe plate and the'scale' 8' and has aflixed 130117118outer-extremity;thereof indicating pointer or; needle 19 whichcooperates with the scale to indicatethe relative humidity. *Alight contiaciile spring 20 is connected at one 'of its endswiththeputer end ofthe second armof the bell gr'ank leyer Hand is anchored at-its upper endt mo n plat 4, being place orm -1y under light tension tourge bell cranklever 15 in a counter clockwise direction, as-viewed in Fig. 4

as tharby Pla e li h -tensi o the cop'ic element, as willlater beexplained.

I Whilevarious hygroscopic elements may be em;- ployed, operativelycbnnectd with the bell crank revel 5,'I"p 1fefr to utilize aflexibleresponlsive element, siih as an maligned, thin rib bon comstructed synthetically a nd having a substantially uniform thicknessand'we'ight. Certain'jpapers having adequate tensile strength have 'been 91111; lfiighlyfeiiicient. A h gmsco 1cp re qn cooperating membersclamped together about one of the ends of the responsive strip X. Itwill be noted that the clip 22 at the upper end of responsive element Xis connected to the bell crank lever at a point closer to the fulcrum ofthe lever than the gear segment l5b. A spiral hair 1 spring 23 isconnected at its inner end with the I8 and its outer endisanchored;

indicator shaft as shown, to the adjacent spacing sleeve Mia. The hairspring the' front of the frame) therebytaking up at all times any playexisting between the gear, segment ISband the pinion l1. I 1Theanchoringarm 2| is pivoted at one of its ends to a suitable pin 24which extends normal to the mounting plate Hi. The opposite end of saidanchoring armis disposed just below a substantially vertical adjustmentscrew 25, which is threadedly mounted in the turned end of a bracket26.. The lower endof adjusting screw 25 engages and determines theposition of the anchoring arm 2!, arm 2| having an adjustment lug orshoulder 2 la which cooperates with the screw; The device may beaccurately set from a master hygrometer of known calibration at thefactory through the adjustment of screw 25, which, of course, varies theanchored position of the hygroscopic element X. For convenience,athermometer T may be secured to the front face of frame 6 below thehygrometer scale. 7

Operation *1 All surfaces of the responsive element X are subjected toair or the other gaseous medium surrounding the device, the air freelycirculating through the interior of the housing by way of the severalslots I 2 and [3. It will be noted that the hygroscopic element isspaced substantiallymidway between the mounting plate 14 and the rearplate It to adequately subject all surfacesof the responsive element tothe circulated air. The flexible responsive element is constantlymaintained under a light tension by means of the con-1 tractilespring 20connected with the outer end of the horizontal bell'crank arm.:Contraction of the responsive element X due to'a decrease in therelative humidity ofthe gaseous medium to' which the element issubjected causes bell crank arm l 5 to be moved slightly in a clock-wisedirection, as seen in Fig,-4. The rotative movement of the bell cranklever i5 is greatly multiplied in its effect upon the indicator shaft l8by means of the relatively large gear ratio present between segment gearI51) and pinion A very slight rotative movement of the bell'crank lever,there fore, will produce a substantial rotative movement on the part ofthe indicator shaft l8. Tointer-IS fixed to indicatorv shaft l8indicates 0n the scale or dialthe, relative humidity at any time interms q s t e I w ,7

E xp ansion of the hygroscopic element); due toanincrease in therelativehumidity of the gas-,

eous mediumto which the same is subjectedpermits the contractile spring20 to movebell crank v the very accurate. means. for

V From the. foregoingdescription it will be seen that I have provided ahighly accurate and cmis arranged to urge the indicator shaft clock-wise(when the deviceis viewed from 1 mi r t ma br 51 It will; ofcours leverIS in counter-clock-wise direction, as seen in Fig. 4, thereby turningindicator shaft I 8 through a much greater rotative movement and in anopposite direction.

The accuracy of my device is exceedingly high 5 due to the relativelyslight rotative movement of lever 15 between the minimum relativehumidity and the maximum relative humidity and due to multiplying thisslightmovement without distortion or error. In this connection thefunction of the hair spring 23 is important in that the indicator shaftis always held to its limit of movement with reference to the meshing ofpinion l1 and gear segment lib.

cient hygrometer which directly indicates the rel- -ati've humidity ofthe air without computation of the data or information. The device isexceedingly sensitive, responding readily and noticeably eath blownffroma distance of six'oreightinches upon 'th li'ygro-i scopic element. 3 "If) Itwill further be seen that the-mechanism of my improveddevice isvery 'simpleand is capable 25 Y of being manufactured at low cost. 1 e,-be understood that" various changes may be made in the form, details;proportions' a'nd arrangement of the'par-ts, without departing from thescope'ofmy invention, which, generally'stated, consists'in a devicecapable of carrying out the objects'above setforth, and in thenovel-parts and combinations of p'artsdisf closed and defined intheappended claims; 'Wh'at isclaimed V 35 1. Ahygrometer having incombination', an elongated flexible hygroscopic element, means foranchoring one end of'said element, an actuating lever f pivoted forswinging movement and having an arm extending substantially at rightangles 40V to the opposite'end of said element; a clip pivotallyconnected with said arm and clamped to said last mentioned end ofsaidhygroscopic; element; said lever rigidly oarryinga gear segmentanactuated shaft ,journaled' forrotative movement a pinion 45 fixedto saidshaftand'meshed' with said gear segment; means connected with said leverfor mainsaid 'elementunder light tension, a lightspiralspringspirally-arranged about saidshaft 50 and connected withsaid'shaft to always maintain said shaft initslimit of. movement in, onedirection relatively to said gear segment,and threaded adjustment meansfor varying theposition 01' said elementfanchoring means.

j l 65 2. A "hygrometer having in combination," a frame, an adjustmentlever pivoted adjacent one end 51 said frameQa flexible hygroscopicelement extendingacross 'a substantial portion of "said frameand spacedtherefrom, a clip pivotally se cured tosaid'adjusjtment lever and clamied to one movement, a pinion fixed to said shaft and meshed v with saidgear segment and indicating means in cluding an indicating element fixedto said shaft.

3. A hygrometer having in combination, a frame, an adjustment leverpivoted adjacent one end of said frame, a flexible hygroscopic elementextending across a substantial portion of said frame and spacedtherefrom, a clip pivotally secured to said adjustment lever and clampedto one end of said hygroscopic element, said. element extendingsubstantially at right angles to said adjustment lever, adjustment meansabutting said adjustment lever to determine the position thereof, anactuating lever pivoted for swinging movement adjacent the upper end ofsaid frame, a clip pivotally connected with said actuating lever andclamped to the other end of said hygroscopic element, a gear segmentfixed to said actuating lever, an actuated shaft journaled for rotativemovement, a pinion fixed to said shaft and meshed with said gearsegment, and indicating means including an indicating element fixed tosaid shaft.

CARROLL E. LEWIS.

